Plan Ceibal - Accessibility & Audio Support

[Nicholas Doiron]

Hi,

I'm working with Plan Ceibal's Content department in Montevideo, Uruguay. 
I showed the Open Video Chat activity to the team today and they are very
excited to use this in their activities on the XO-1.5 HS.

In order to use the activity for English lessons, the team would be
interested in researching a way to add audio.  I have worked with the XO
microphone and H.264 encoding/decoding on separate projects, so I might be
able to make some progress on this front.  If not, Plan Ceibal has several
engineers who could take on the project.

Could you let us know whether the activity is still in development, and
what the main roadblocks are to adding an audio stream?

Regards,
Nick Doiron

[Justin Lewis]

The activity at the moment is on hold as our dev team is dealing with
class work at the moment.

When we were working on the project we found that we were unable to
maintain an audio and video connection on the xo at any usable rate.
Most of the cpu was being used to manage the video.

Some of the major problems we had were bugs in gstreamer/telepathy
that were not being ported to the version running on the xo's.

Now that there are some more modern builds on the xo many of these
gstremer bug fixes may be available on the xo.

One of the major bugs we were facing was preventing us from using
telepthathy/farsight's rtp with available codec's on the system.  This
forced us to use an xvimage sink and a ximagesink.  As the ximage sink
is not accelerated the cpu had to take up the slack.

I think if the rtp protocol bugfix is available to the xo, then the
ximage sink can be dropped freeing up the cpu to allow time for audio
muxing.  The rtp protocol will allow us to start both video feeds and
not worry about the header of the stream to be lost.  By ensuring the
header will not be lost we can start both the sending and receiving
feeds at the same time and push them to the xvimage sink.

I hope that gives you a basic idea of the state of the project if you
have any questions let me know.  I am just getting ready for
graduation so my responses may be a delayed a few days (like this
one), but I'll do the best I can.

Justin Lewis
http://jlewopensource.com



On Tue, Apr 26, 2011 at 2:22 PM, Nicholas Doiron <ndoiron(a)andrew.cmu.edu&gt; wrote:
>  Hi,
>
>  I'm working with Plan Ceibal's Content department in Montevideo, Uruguay.
>  I showed the Open Video Chat activity to the team today and they are very
>  excited to use this in their activities on the XO-1.5 HS.
>
>  In order to use the activity for English lessons, the team would be
>  interested in researching a way to add audio.  I have worked with the XO
>  microphone and H.264 encoding/decoding on separate projects, so I might be
>  able to make some progress on this front.  If not, Plan Ceibal has several
>  engineers who could take on the project.
>
>  Could you let us know whether the activity is still in development, and
>  what the main roadblocks are to adding an audio stream?
>
>  Regards,
>  Nick Doiron
>
>  _______________________________________________
>  Ovc mailing list
>  Ovc(a)lists.fedorahosted.org
>  https://fedorahosted.org/mailman/listinfo/ovc
>

[Nicholas Doiron]

Thank you so much!  This is the first time I've heard of ximage, but now I
know where to start.

If I can't get bug fixes onto Uruguay's latest XO builds, I might try
"push to talk" and send audio files instead of streaming.

Regards,
Nick Doiron

On Wed, April 27, 2011 1:51 pm, Justin Lewis wrote:
>  The activity at the moment is on hold as our dev team is dealing
> with
>  class work at the moment.
>
>  When we were working on the project we found that we were unable to
>  maintain an audio and video connection on the xo at any usable rate. Most
>  of the cpu was being used to manage the video.
>
>  Some of the major problems we had were bugs in gstreamer/telepathy
>  that were not being ported to the version running on the xo's.
>
>  Now that there are some more modern builds on the xo many of these
>  gstremer bug fixes may be available on the xo.
>
>  One of the major bugs we were facing was preventing us from using
>  telepthathy/farsight's rtp with available codec's on the system.  This
>  forced us to use an xvimage sink and a ximagesink.  As the ximage sink is
>  not accelerated the cpu had to take up the slack.
>
>  I think if the rtp protocol bugfix is available to the xo, then the
>  ximage sink can be dropped freeing up the cpu to allow time for audio
>  muxing.  The rtp protocol will allow us to start both video feeds and not
>  worry about the header of the stream to be lost.  By ensuring the header
>  will not be lost we can start both the sending and receiving feeds at the
>  same time and push them to the xvimage sink.
>
>  I hope that gives you a basic idea of the state of the project if you
>  have any questions let me know.  I am just getting ready for graduation so
>  my responses may be a delayed a few days (like this one), but I'll do the
>  best I can.
>
>  Justin Lewis
>  http://jlewopensource.com
>
>
>
>
>  On Tue, Apr 26, 2011 at 2:22 PM, Nicholas Doiron <ndoiron(a)andrew.cmu.edu&gt;
>  wrote:
>
> >
> > Hi,
> >
> >
> > I'm working with Plan Ceibal's Content department in Montevideo,
> > Uruguay.
> > I showed the Open Video Chat activity to the team today and they are
> > very excited to use this in their activities on the XO-1.5 HS.
> >
> > In order to use the activity for English lessons, the team would be
> > interested in researching a way to add audio.  I have worked with the XO
> >  microphone and H.264 encoding/decoding on separate projects, so I
> > might be able to make some progress on this front.  If not, Plan Ceibal
> > has several engineers who could take on the project.
> >
> > Could you let us know whether the activity is still in development, and
> >  what the main roadblocks are to adding an audio stream?
> >
> > Regards,
> > Nick Doiron
> >
> >
> > _______________________________________________
> > Ovc mailing list
> > Ovc(a)lists.fedorahosted.org
> > https://fedorahosted.org/mailman/listinfo/ovc
> >
> >
>
>

[Benjamin M. Schwartz]

On 04/27/2011 02:04 PM, Nicholas Doiron wrote:
>  If I can't get bug fixes onto Uruguay's latest XO builds, I
> might try
>  "push to talk" and send audio files instead of streaming. 
In general, I would urge you to forget about video, and focus on doing
audio well.  Audio chat (VoIP) is a fundamental missing feature in Sugar/OLPC.

On XO-class hardware (even XO-1.5), video chat will never really work
well.  There simply isn't enough CPU power to encode and decode good
quality audio and video simultaneously.  In poor schools were Sugar is
used, there also isn't enough internet bandwidth (video requires a huge
amount of bandwidth).*

In contrast, there is plenty of CPU, and maybe even plenty of bandwidth,
for good quality voice transmission.  Voice chat is also well-supported in
Telepathy, as it is used by Empathy.

Push-to-talk is certainly an interesting idea, but it's a poor substitute
for a real (VoIP) telephone conversation.  If you do decide to implement
push-to-talk, the most interesting thing would be to implement as a
feature of Sugar that works in any shared activity.  This way, any group
of people who are working together via the collaboration mechanism can
also talk about what they're doing.

--Ben

*: These challenges are worth tackling for the OVC group because their
users, deaf students, cannot use a VoIP phone.